1. Field of the Invention
The invention relates to thread handling systems for lockstitch sewing machines.
2. Description of the Prior Art
U.S. Pat. No. 4,263,859 of Ralph E. Johnson for "Thread Handling System for a Sewing Machine", issued Apr. 28, 1981, discloses a thread handling system which includes a thread holder with elongate members that grasp and meter thread to a needle and looptaker of a lock-stitch sewing machine. The system further includes a tensioning device without a check spring. Thread from a source extends to the tensioning device, and beyond the tensioning device the thread extends to the thread holder. Beyond the thread holder the thread extends to the needle. A takeup, which brackets the thread holder, sets stitches and pulls thread through the tensioning device. The takeup moves the thread in one direction in the holder to a stitch position at one end of its operating range, and moves in the opposite direction free of thread to the other end of its operating range, after which thread in the holder moves to a position of reengagement with the takeup to shorten the path for thread between the tensioning device and needle such that a quantity of thread is thereby supplied for use by the needle and looptaker. The tensioning device is disposed to one side of the elongated members of the thread holder in a position relative to the operating limits of the takeup to enable thread while the takeup is in the said other end of its operating range to be withdrawn from the tensioning device without being pulled from the thread source and with less tension in the thread than when pulled from the thread source by operation of the takeup.